Structure having coincidence of normally eccentric axes of force and mass



" March 20, 1928.

H. F. ROACH STRUCTURE HAVING COINCIDENCE 0F NORIALLY ECCENTRIC AXES 0 SSF FORCE AND BM Filed 001;. 31, 1927 C vzvvroe:

J/ARRY E BOA Ch- 5 Arman 1:545

Patented Mar. 20, 1928.

UNITED STATES PATENT OFFICE.

HARRY F. ROAGI-I, OF ST. LOUIS, MISSOURI.

STRUCTURE HAVING GOINGIDENCE OF NORMALLY ECCENTRIC axes or roncn ANDmass.

Application filed. October 31, 1927. Serial No. 229,943.

This invention relates to the production of integral structures havingan unsymmetrical section on an axis and which, due to the action ofinternal forces, are subject to sponding. The structure may be any massI which, as an element, is of unsymmetrical section on at least oneco-ordinate.

A balanced internal force, the energy of which is exerted in the sameco-ordinate planes as an external force, will have the same effect onthe structure if the signs of the resultant forces are as those of theexternal forces and will bear the same relation to the center of gravityof the structure.

If the signs of the resultant forces are opposite to those of theexternal force, then the effect on the structure is that of tensionrather than compression, but the work done is the same. i

The present invention is'concerned with the efi'ect'of internal forceexerted within a structure, and has for its general object theproduction of structures unsymmetrical on at least one co-ordinate, inwhich the position of the effective resultant of internal forces shallcoincide with the center of gravity or geometrical neutral axis of thestructure. This position of the eifective resultant force in astructure, I have designated the metallurgical neutral axis, and it is afurther object of the invention to provide a novel method of determiningthe position of this metallurgical neutral axis in a given structure,and by re-designing, or TG-CllStllbuting the mass of, the'structure, tosecure coincidence of the metallurgical neutral axis with thegeometrical neutral axis of the structure.

While not, in. any sense, limited thereto, my invention will probablyfind its widest application in the manufacture of steel rails, and theaccompanying sheet of drawing illustrates my invention as embodied in arail structure.

In said. drawin Figure 1 i4 .rth section of a rail heat, water,electricity, light,

. they may jected in perspective, the rail being one of a standardconstruction;

Figure 2 is asimilar view showing a rail of this standard in which thearea of the base section is the same as that of Fig. 1, but having aless amount of metal in the head in order to cause the metallurgicalneutral axis to I coincide with the geometrical neutral axis;

Figure 8 is a similar view of a rail of the same standard showing theamount of metal in the base increased relative to that in the head, forthe same purpose;

Figure 4:,is a similar view of a rail of the same standard showing are-distribution of the metal in both the head and base of the rail tobring about the coincidence of the metallurgical neutralaxis with thegeo metrical neutral axis, as in Figs. 2 and 3, but in which the area ofthe head of the rail shown in Fig. 1 is preserved; and

Figure 5 is a diagrammatic view in end elevation of one-half of a railwith indications thereon showing the manner of dividing a: rail intosections for thepurpose of detlermining the metallurgical axis of the maIn Fig. 1, I have shown two lines with arrowheads at either end of therail pointing in opposite directions, and which are designated,respectively, by the letters G. N. A, representing the geometricalneutral axis, and the letters M. N. A., representing the metallurgicalneutral axis. The position of the latter is conditioned by internalforces, but for the purpose of illustration, be considered as externalforces operating at opposite ends of the rail. These lines, or axes, areshown to be out of coincidence. If, now, an external force'be appliednormal to the section at the center of gravity of the section,represented by the line G. N. A. at the left and is opposed by an equalforce at the opposite face and lying in the same co-ordinate planes,represented by the line G. N. A. at the right of Fig. 1, thencompression exists and no general distortion of the rail will resultother than direct compression diminution in di mension.

If the same force conditions are applied but located below oneco-ordinate plane and in the other co-ordinate plane, as i lustrate bythe line G. N. A. at the left of Fig. 1

*turingrails, and after leaving the cooling.

and the line llipllrfi. at the right of Fig. 1, the -rail will assume adistortedcondition, as illustrated by the dotted lines in such figure.This arched condition of the rail is normal in the present processes ofmanufacthe rail requires that the rail be bent beyonc its elastic limitin order to give a permanent set. Such bending of the rail beyond itselastic limit-uses up approximately forty I per cent or more'oi thestrength ofthei rail before it is put in the track. Furthermore, 1 atthe' points otgagging, small nuclei are 'foundyand it is my opinion thatunder roll- =ing load and weaving of the rail, these are developed intotransversc fissures, causing the rail to break. These transversefissures are very'deceptive and unsafe and have been the subject ofinvestigation and research by skilled engineers for many years 1 Withoutany scientific cause for their presence being discovered and without anymeans being devised for preventing their occurrence. l/Vhile my opinionis as above, I am not in a position to aiiirm unqualifiedly that trans-"verse fissures in rails are caused as a result of 'gagging the rails.However, the weakening of'the rail resulting' from bending it be yondits'elastic li1nit,*at present anecessary evil existing in themanufacture o'f'rails, is obviously something which should be avoided ifpossible, and this, it is the main object of my invention to accomplish.

In the manufacture of steel rails, heat is necessarily involved. J Theheat expands the metal and the removing of heat contracts the metal. Theforce involved is the same in ;both cases, although the sign isdifferent. The position of the effective resultant of this cooling forcevaries with the design -ef section of the structure; it maybe a point, aline, or a plane.

From what has been stated above, it-will be clear that if the centerotgravity or geometrical neutralaxis of the" rail section of Fig. 1 ismade to coincide with what I have termed, and designated in said figure,the metallurgical neutral axis, then a force applied to the sectionatthe line A.,

'01 its center of gravi y, and opposed by an 'equal force at theopposite face of the rail applied-at the lineof its metallurgicalneutralaxis will produce no distorti'onot the rail, but only'eompression. Tobring about this-coincidence of the metallurgical with the geometricalneutral'ax-es of the rail, I

proceed in the following manner:

In the case of a rail, I would first ascertain the position of thegeometrical neutral axis .of' the rail, which is done according to aWellknown method, and said axis may be indicated by the line aa in Fig.5. I next divide the rail into three sections, as indicated by the linesZ -b and 0, the three sections'being indicated, respectively, by thenumerals 1, 2 and 3. It will be understood,

of course, that for. this purpose, the rail can be divided into anynumber of sect-ions.

next, ascertain the center of gravity-of the respective sections, dividethe perimeter of I. each section by the area thereotto :obtain thecooling power of eachsection, then multiplyeach. of the respectivecooling powers by-the distance of the centerof gravity of each areafrom. a plane of selection and divide the sum of these products by thesum of the respective cooling powers. This will .give the position ofthe resultant'force of tion and re-compute. By making two or morealterations and coinputations,a sequence is established that permitsexact determination of the .point, line,.or plane of coincidence notthe; geometrical neutral axis and the met all urgical neutral axis.

In Fig. 1, I have indicated, for the purpose of 00111139118011, thecenter of the web .4. of the rail by a line (Z(Z, and it will be seenthat the line 01? the geometrical neutral axis islocated above the linecZ-(Z, while the line of metallurgical. neutral axis is lo cated belowit. By observing Fig.2 in which, according to themethcd above outlined,the head 5 of the rail hasbeen re-designed to bring aboutcoincidence oithe geometrical and metallurgical neutral it-will. be seen that thiscommon axis is located below the linerkal. Thus, it will be observedthat alteration of the section of Fig. 1 that caused the movement of thegeometrical neutral axes in one direction causes the movement of themetallurgical neutral axis in the reversedirection,

-so that no matter what the character of the structure involved, apoint, plane, or. line exists, and only one, where the resultant of thecooling forces and the center of gravity of the section coincide.

In both Figs. 3 and 4,.tliegeometrical, and

metallurgical neutral. axes. of the respective rails coincide, as inFig. 2, the only difi'erence being that in Fig. .3, the: area of thebase 6.1ias been increased relative to that of the head 7 to bring aboutthe coincidence of the two axes, while in Fig. 4:, the area of the head8 is the same as that of the head of the rail illustrated in Fig. 1 andthe area of the base of the rail 9 has been correspondingly enlarged tobring about coincidence of the two axes. In the three structures ofFigs. 2, 3 and 4, the thickness of the web of the rail is maintainedsubstantially constant to minimize internal strains.

From all of the above, it will be apparent to those skilled in the artthat by designing the rail section in the'manner described to bringabout a coincidence of the metallurgical neutral axis with thegeometrical neutral axis or center of gravity of the rail, op portunityis offered straight and thereby retain the full measure of its designedstrength, and by avoiding the necessity of bending the rail straightafter it is cooled, to prevent the cause of uncertain and unsafe zonesin the rail incident to gagging.

WVhile, for convenience, I have referred to changing the areas of thehead and base of the rail, respectively, it will be understood that suchalterations as to the head would correspond to altering section 1 ofFig. 5, and such alterations as to the base of the rail, to alteringsection 3 of Fig. 5.

Iclaim:

1. A structure havin at least one unsymmetrical section and subject tothe efiect of forces tending to distort it, in which the geometricalneutral axis of the structure and the metallurgical neutral axis arecaused to coincide. r

2. A structure having at least one unsymmetrical section and subject tothe effect of forces tending to distort it in the process ofmanufacture, in which the geometrical neut-ral axis of the structure andthe metallurgical neutral axis are caused to coincide.

3. The herein described method, which consists in determining thegeometrical neutral axis of a structure having an unsymmetrical sectionon one co-ordinate, ascertaining the position of the metallurgicalneutral axis of said section relative to its geometrical neutral axis,and changing the mass 0 one element of said section to bring about 00-.incidence between the metallurgical and geometrical neutral axes of thesection.

l. The herein described method, which consists in determiningthegeometrical neutral axis of a structure having an unsymmetricalsection on one co ordinate, ascertaining the position of themetallurgical neutral axis of said section relative to its geometricalneutral axis, and re-distributing the mass of said structure to bringabout coincidence between for the rail to cool.

the metallurgical and geometrical neutralaxes of the section.

5. The herein described method, which consists in determining thegeometrical neutral axis of a structure having an unsymmetrical sectionon one co-ordinate, ascertaining the position of the metallurgicalneutral axis of said section relative to said geometrical neutral axis,and if eccentricity exists, ing the section and re-co'mputing, and repeating this process until a sequence is established that permits exactdetermination o the point, plane or geometrical neutral axis and themetallurgical neutral axis.

6. A structure, the section of which is unsymmetrical on an axis and inthe manufacture of which an internal force is involved, the resultantaxis of the force and the geometrical neutral axis of the mass being substantially coincident.

7. A structure of unsymmetrical masson an axis and in which an internalforce is involved, the resultant point of the force being substantiallycoincident with the center of gravity of the mass.

line of coincidence of the alter- I 8. A structure having a section ofunsym metrical distribution of metal on an axis and which is heated andsubsequentlypermitted to cool in the process of manufacture, in whichthe metallurgical neutral axis and the geometrical neutral axissubstantially coincide.

9. A rail having asection of unsymmetrical distribution of metal on anaxis and which is heated and permitted to cool in the process ofmanufacture, in which the metallurgical neutral axis and the geometricalneutral axis substantially coincide, the web of said rail section beingof substantially constant thickness to minimize internal strains. I

10. A structure having a section unsymmetrical on an axis, the center ofsummation of the mass about a point being substantially the same as theresultant of internal forces in said structure present during theprocess of manufacture thereof.

11. The herein described method which consists in determining theposition of a resultant internal force due to its presence andsubsequent elimination or diminution during the process of manufactureof a struc ture, and determining the relation of the position of theresultant internal force to the center of gravity of the structure.

In testimony whereof, I have hereunto set my hand.

HARRY F. ROACH.

